Japanese patent application no. 2001-243535 filed on Aug. 10, 2001 is hereby incorporated by reference in its entirety.
The present invention relates to a power control circuit, an electronic instrument, and a charging method.
It is usual for a portable electronic instrument such as mobile phones to be battery-powered, and it is necessary to provide a dedicated AC adapter or charger for charging a rechargeable battery (a chargeable storage battery, or secondary battery) thereof. It often happens that such an AC adapter or charger cannot be used in a portable electronic instrument of different types (made by the same manufacturer or another manufacturer). For that reason, when the possessor of a plurality of portable electronic instruments goes out, it is necessary to carry a number of AC adapters or chargers, which is inconvenient.
Recently, the universal serial bus (USB) standard has suddenly permeated the marketplace, as an interface standard for connecting a personal computer (hereinafter called xe2x80x9cPCxe2x80x9d) to its peripherals. This USB standard has the advantage of enabling the use of connectors of the same standard to connect a peripheral instrument such as a mouse, keyboard, and printer, which are connected by connectors of different standards in the prior art, and of making it possible to implement plug-and-play and hot-plug features.
In addition to data lines (D+ and Dxe2x88x92), a USB cable has power lines (VBUS and GND). Use of these power lines in the USB cable makes it possible to charge a portable electronic instrument such as mobile phones, and techniques disclosed in Japanese Patent Application Laid-Open Nos. 2000-339067 and 2000-201204 are known as prior-art techniques relating to such a charging method.
However, these prior-art techniques necessitate dedicated connectors and control circuits for connecting the USB cable to a portable electronic instrument such as a mobile phone, so that a general-purpose USB cable alone cannot be used for connecting a PC and the portable electronic instrument.
In addition, these prior-art techniques dictate that the side that supplies power for charging a rechargeable battery (the source of the power for charging) is fixed as the PC acting as host, and the side that charges the rechargeable battery with the power supplied from the charging power is fixed as the portable electronic instrument that is the device (function or target). It is therefore not possible to set an electronic instrument to be either the source that supplies the charging power or the destination of that charging power. A problem arises in that a PC which is a host must always be used when using a USB cable to charge a rechargeable battery of a portable electronic instrument.
One aspect of the present invention relates to a power control circuit used in an electronic instrument that is provided with a universal serial bus (USB) interface,
wherein when the electronic instrument has been set to a slave side for USB data transfer and has been set to normal operating mode, the power control circuit supplies power from a USB power line, power from a rechargeable battery, or power from an external power source to a data transfer control circuit which controls USB data transfer; and
wherein when the electronic instrument has been set to the slave side for USB data transfer and has been set to charge mode, the power control circuit supplies power from the USB power line to the rechargeable battery of the electronic instrument in order to charge the rechargeable battery.
Another aspect of the present invention relates to a power control circuit used in an electronic instrument that is provided with a universal serial bus (USB) interface,
wherein when the electronic instrument has been set to a master side for USB data transfer and has been set to normal operating mode, the power control circuit supplies power from a rechargeable battery or power from an external power source to a data transfer control circuit which controls USB data transfer; and
wherein when the electronic instrument has been set to the master side for USB data transfer and has been set to charge mode, the power control circuit supplies power from the rechargeable battery or power from the external power source to another electronic instrument on a slave side through a USB power line, in order to charge a rechargeable battery of the other electronic instrument on the slave side connected to the electronic instrument by USB.
A further aspect of the present invention relates to a power control circuit used in an electronic instrument that is provided with a universal serial bus (USB) interface,
wherein when the electronic instrument has been set to a slave side for USB data transfer and has been set to normal operating mode, the power control circuit supplies power from a USB power line, power from a rechargeable battery, or power from an external power source to a data transfer control circuit which controls USB data transfer;
wherein when the electronic instrument has been set to the slave side for USB data transfer and has been set to charge mode, the power control circuit supplies power from the USB power line to the rechargeable battery of the electronic instrument in order to charge the rechargeable battery;
wherein when the electronic instrument has been set to a master side for USB data transfer and has been set to normal operating mode, the power control circuit supplies power from the rechargeable battery or power from the external power source to the data transfer control circuit which controls USB data transfer; and
wherein when the electronic instrument has been set to the master side for USB data transfer and has been set to charge mode, the power control circuit supplies power from the rechargeable battery or power from the external power source to another electronic instrument on the slave side through the USB power line, in order to charge a rechargeable battery of the other electronic instrument on the slave side connected to the electronic instrument by USB.